A basic process for the production of arylene sulfide polymers from polyhalo-substituted aromatic compounds by reaction with an alkali metal sulfide in a polar organic solvent is disclosed in U.S. Pat. No. 3,354,129. Since then much work has been done to provide methods of modifying or controlling the melt flow rate of poly(arylene sulfide) thus produced. For example, the use of curing or chain extension reactions in post polymerization processes are known for decreasing the melt flow rate. In addition, the use of alkali metal carboxylates and/or polyhalo-substituted aromatic compounds having 3 or more halogen atoms per molecule in the polymerization reaction mixture also is known to reduce melt flow rate. In these illustrations noted above it is generally considered that a melt flow rate is inversely related to molecular weight. Extrusion rate, which is more specifically defined hereinafter, is a specific type of melt flow rate particularly useful for characterizing arylene sulfide polymers in the lower molecular weight range.
However, there is a need for poly(p-phenylene sulfide) of high extrusion rate in such fields as electronic encapsulation. Methods for reproducibly producing such high extrusion rate polymers are at present unsatisfactory for various reasons such as increased cost of added reactant materials, need for recycling excess reactants or risking completely off-spec polymer by slight mistakes in charging reaction ingredients.
It is therefore an object of this invention to provide a method for producing poly(p-phenylene sulfide) having a high extrusion rate in a readily controllable manner. It is another object of this invention to provide a method for producing poly(p-phenylene sulfide) having a high extrusion rate by adjustment of a reactant ratio in the reaction mixture. It is another object of this invention to provide a method for producing poly(p-phenylene sulfide) having an extrusion rate of about 100 to about 1,000 g/10 min.